Atomic radiation detector



Feb. 28, 1956 H. J. MARSHALL 2,736,815

ATOMIC RADIATION DETECTOR Filed Feb. 12, 1952 7;;1725-5 E'iiii-EEEEEEEEEE 3nnentor Hamilton L- T Mar'sha11 (Ittorneg;

United States Patent:

ATOMIC RADIATION DETECTOR Hamilton L. J. Marshall, Mobile, Ala., assignor to International X Ray, Inc., Mobile, Ala., a corporation of Alabama Application February 12, 1952, Serial No. 271,085

6 Claims. (Cl. 250-78) This invention relates to directional indicating instruments for the detection of atomic radiations.

The primary object of this invention is the provision of an instrument adapted for the emergency directional detection of radioactivity produced by nucleonic fission wherein means is provided to exclude substantially all oblique rays, and to limit the radioactivity detection to rays which enter the instrument forwardly therefrom and substantially parallel to the axis of the instrument.

A further object of this invention is the provision of improved means associated within an atomic radiation detector for the exclusion of rays coming from the rear of an observer lookingthru the instrument.

A further object of-this invention is the provision of a very small compact and efficient type of instrument for the emergency directional detection of radioactivity, such as is incidental to nucleonic fission; the same being relatively cheaply constructed for the eflicient detection of rays which emanate substantially entirely forwardly of the instrument.

Other objects and advantages of this invention will be apparent during the course of the following detailed description.

In the accompanying drawing, forming a part of this specification, and wherein similar reference characters designate corresponding parts throughout the several views:

Figure 1 is a side elevation of the improved atomic radiation detector.

Figure 2 is an end elevation of the detector looking at the sighting end of the instrument.

Figure 3 is a longitudinal cross sectional view taken thru the improved instrument.

Figure 4 is a vertical cross sectional view taken thru the instruments substantially on the line 4-4 of Figure 3.

' Figure 5 is a cross sectional view taken substantially on the line 5-5 of Figure 3.

Figure 6 is an elevation of the front end of the instrument.

This application is a continuation-in-part of my copending application Serial No. 196,603, filed November 20, 1950, now abandoned.

In the drawings the letter A may generally designate the improved instrument. It preferably includes a nucleonic barrier type plastic casing structure 20 which consists of a main elongated body portion 10, of uniform diameter, having the forward end opening lland flanged at 12 to define a shoulder 13 for a purpose to be subsequently described. The casing structure 20 has a cylindrical shaped rear end 14 integrally connected by a tapered or flaring portion 15 with the body 10. The portion 14 is the sighting end of the instrument and it has a chamber 16 therein which is approximately 1% in diameter, although not necessarily to be limited thereto. The plastic of the casing structure 20 is self-susraining and in over-all length the instrument is substantially 3 /2 although not necessarily to be limited there'- to. These dimensions are given merely to show the smallness and compactness of the device, since it can be readily carried in the pocket of an observer for emergency use.

The compartment 16 in the sighting end 14 of the casing structure 20 gradually decreases in diameter at 16* along the tapered portion 15 and the body portion 19 has a chamber 10 therein of uniform diameter from the shoulder 13 to the flaring portion 15. p

The interior of the casing 20 from the flaring end 15 along the body 10 to the shoulder 13 is preferably provided with sharp edged ribs 25.

In the body portion compartment 10 there is disposed a tube 10 of a material having a high radiation absorption coefficient, such as lead, nucleonic barrier type of plastic, etc.

The tube 10 is cylindrical in shape and is held in place in the chamber 10 by the ribs 25 which bite into the external surfacing of the tube 10 as it is pushed into place towards the seat 13. A thin plastic diaphragm or disc 36 is placed in closing relation at the front end of the tube, marginally seating against the shoulder 13 and the tube 29 seats at its forward margin against the disc, as shown in Figure 3. The rear end of the tube 29 is counterbored at 35 and therein is disposed a disc 36 of lead glass. It preferably is transparent but may be slightly translucent. Forwardly of the glass 36 is a screen 37 of fluorescent material, either applied upon the surfacing of the glass 36 or separately and held in place by the fixed positioning of the glass 36 in the counterbore 35. The lead glass disc 36 is radiation absorbing and prevents the screen from fluorescing under radiations emanating from the rear of the instrument penetrating thru the head of the observer. It will be noted that the fluorescing screen 37 is placed a considerable distance from the forward end of the tube 29. This permits substantially only radiations entering the instrument to the screen which are parallel to the axis of the tube 29. Substantially all oblique radiations are prevented from reaching the screen 37, and this renders the instrument highly directional forwardly. If any oblique rays impinge upon the fluorescent screen, such are limited to those which enter the instrument at a very slight acute angle to the axis of the instrument, and of course the farther the screen is disposed from the front end of the tube 29 the smaller will be this angle.

At the sighting end of the plastic casing 10 the latter is contoured for fitting snugly against the observers face, so as to exclude all light from the chamber 16; this contouring including an outer side lip portion 50 which extends rearwardly a greater distance than the inner side lip portion 51. The latter fits at the inside of the eye adjacent to the nose and of course the top and bottom edging 52 is concavely contoured; the edging 53 at the rear of the slide lips 50 and 51 is convexed.

The fluorescent screen 37 is of a material capable of conversion of the X-ray quanta into fluorescence. Such material, referred to as a phosphors can be composed of crystals of calcium fluorite, sodium iodide, thalliumactivated, anthracene, calcium tungstate, calcium sulphide, lead barium sulphate or other inorganic crystal having the ability to fiuoresce in the entire band of the radiation spectrum.

Various changes in the shape, size and arrangement of parts may be made to the form of invention herein shown and described, Without departing from the spirit of the invention or scope of the claims.

I claim:

1. An instmunent for emergency directional detection of radio-activity produced by nucleonic fission comprising an elongated casing structure having a sighting end and including therein a tube having a chamber which is elongated, said tube being formed of a material having a high radiation absorption coefficient, and a fluorescent screen capable of fiuorescing under the influence or" radiation produced as a result of nucleonic fission disposed in a transverse plane across and within said tube at a distance appreciably to the rear of the fore end of said tube whereby to exclude substantially all rays except those Which are substantially parallel to the axis of said tube.

2. An instrument such as described in claim 1 wherein a diaphanous member is disposed adjacent to and across said screen to the rear thereof, said member being of a material having a high radiation absorption coefficient whereby to exclude radiations to the rear of an observer looking thru said instrument.

3. An instrument for detecting radioactivity comprising an elongated plastic casing of a nucleonic barrier type of plastic, an elongated lead tube mounted within and circumferentially and longitudinally lining said plastic casing, and a transverse fluorescent screen capable of fluorescing under the influence of radioactivity disposed in said lead tube spaced appreciably from the forward end of the lead tube so that only radiations substantially parallel to the axis of said tube can impinge directly upon said screen, said casing and tube having sighting openings to the screen adjacent to the latter.

4. An instrument such as described in claim 3 wherein a transparent lead glass member having a high radiation absorption coefficient is disposed across and adjacent to said screen to the rear thereof for the purpose of excluding radioactivity to the rear of said instrument.

5. An instrument for emergency directional detection of radioactivity comprising an elongated casing structure having an elongated passageway therethrough with facing material within the passageway extending therealong having a high radiation absorption coefficient, the forward end of said passageway being unobstructed by said high radiation absorption coeflicient material whereby to permit rays to enter said passageway in substantial parallelism with the axis of the passageway to exclusion of oblique rays, said casing structure at its rear end having a sighting opening shaped to fit closely around an eye of an observer so as to exclude light from entering at said sighting end, said casing structure at the rear of said passageway having a transverse fluorescent screen located remotely from the front ray entrance end of said casing structure whereby substantially only parallel rays may impinge thereon, and a transparent lead glass disc having a high radiation absorption coefiicient disposed transversely across and immediately to the rear of said fluorescent screen for the purpose of excluding radioactivity entering the casing structure from the sighting end thereof.

6. An instrument for directional detection of radioactivity comprising an elongated casing structure of cylindricm formation and substantially uniform diameter from end to end, formed of plastic material having a high radiation absorption coeificient, an elongated lead tube circumferentially and longitudinally lining the passageway of the plastic tube throughout substantially the length thereof, a thin diaphragm closing the forward ends of the passageways of the said tubes, a fluorescent disc screen located across the rear ends of the passageways of said tubes, a transparent lead glass disc having a high radiation absorption coefficient transversely disposed across and immediately to the rear of the fluorescent screen for excluding rays from entering the casing structure from its rear end, the diameters and lengths of said tubes being such that only rays which are substan-, tially parallel with the axis of the passageway of the lead tube will be permitted to have direct access to the flourescent screen, said casing structure at the rear end thereof having a substantially cylindrical shaped extension provided with a sighting opening shaped to fit closely around the eye of an observer.

References Cited in the file of this patent UNITED STATES PATENTS 1,385,696 Marshall et al July 26, 1921 1,596,328 Wilt Aug. 17, 1926 2,290,767 Renter July 21, 1942 2,513,805 Kanne July 4, 1950' 2,578,703 Hopkins et al Dec. 18, 1951 2,666,856 Fua et al. Jan. 19, 1954 OTHER REFERENCES Radiology, vol. 27, 1936, page 152. 

1. AN INSTRUMENT FOR EMERGENCY DIRECTIONAL DETECTION OF RADIO-ACTIVITY PRODUCED BY NUCLEONIC FISSION COMPRISING AN ELONGATED CASING STRUCTURE HAVING A SIGHTING WHICH END AND INCLUDING THEREIN A TUBE HAVING A CHAMBER WHICH IS ELONGATED, SAID TUBE BEING FORMED OF A MATERIAL HAVING A HIGH RADIATION ABSORPTION COEFFICIENT, AND A FLUORESCENT SCREEN CAPABLE OF FLUORESCING UNDER THE INFLUENCE OF RADIATION PRODUCED AS A RESULT OF NUCEONIC FISSION DISPOSED 